# Copyright 2023 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Rules to build Kelvin SW objects"""

load("@rules_cc//cc:find_cc_toolchain.bzl", "find_cc_toolchain")

KELVIN_PLATFORM = "//platforms/riscv32:kelvin"

def _kelvin_transition_impl(_settings, _attr):
    return {"//command_line_option:platforms": KELVIN_PLATFORM}

kelvin_transition = transition(
    implementation = _kelvin_transition_impl,
    inputs = [],
    outputs = ["//command_line_option:platforms"],
)

def kelvin_rule(**kwargs):
    """Kelvin-specific transition rule.

    A wrapper over rule() for creating rules that trigger
    the transition to the kelvin platform config.

    Args:
      **kwargs: params forwarded to the implementation.
    Returns:
      Kelvin transition rule.
    """
    attrs = kwargs.pop("attrs", {})
    if "platform" not in attrs:
        attrs["platform"] = attr.string(default = KELVIN_PLATFORM)
    attrs["_allowlist_function_transition"] = attr.label(
        default = "@bazel_tools//tools/allowlists/function_transition_allowlist",
    )

    return rule(
        cfg = kelvin_transition,
        attrs = attrs,
        **kwargs
    )

def _kelvin_binary_impl(ctx):
    """Implements compilation for kelvin executables.

    This rule compiles and links provided input into an executable
    suitable for use on the Kelvin core. Generates both an ELF
    and a BIN.

    Args:
      ctx: context for the rules.
        srcs: Input source files.
        deps: Target libraries that the binary depends upon.
        hdrs: Header files that are local to the binary.
        copts: Flags to pass along to the compiler.
        defines: Preprocessor definitions.
        linkopts: Flags to pass along to the linker.

    Output:
        OutputGroupsInfo to allow definition of filegroups
        containing the output ELF and BIN.
    """
    cc_toolchain = find_cc_toolchain(ctx).cc
    feature_configuration = cc_common.configure_features(
        ctx = ctx,
        cc_toolchain = cc_toolchain,
        requested_features = ctx.features,
        unsupported_features = ctx.disabled_features,
    )
    compilation_contexts = []
    linking_contexts = []
    for dep in ctx.attr.deps:
        if CcInfo in dep:
            compilation_contexts.append(dep[CcInfo].compilation_context)
            linking_contexts.append(dep[CcInfo].linking_context)
    (_compilation_context, compilation_outputs) = cc_common.compile(
        actions = ctx.actions,
        cc_toolchain = cc_toolchain,
        feature_configuration = feature_configuration,
        name = ctx.label.name,
        srcs = ctx.files.srcs,
        compilation_contexts = compilation_contexts,
        private_hdrs = ctx.files.hdrs,
        user_compile_flags = ctx.attr.copts,
        defines = ctx.attr.defines,
    )
    linking_outputs = cc_common.link(
        name = "{}.elf".format(ctx.label.name),
        actions = ctx.actions,
        feature_configuration = feature_configuration,
        cc_toolchain = cc_toolchain,
        compilation_outputs = compilation_outputs,
        linking_contexts = linking_contexts,
        user_link_flags = ctx.attr.linkopts + [
            "-Wl,-T,{}".format(ctx.file.linker_script.path),
            "-Wl,--no-warn-rwx-segments",
        ],
        additional_inputs = depset([ctx.file.linker_script] + ctx.files.linker_script_includes),
        output_type = "executable",
    )

    binary = ctx.actions.declare_file(
        "{}.bin".format(
            ctx.attr.name,
        ),
    )
    ctx.actions.run(
        outputs = [binary],
        inputs = [linking_outputs.executable] + cc_toolchain.all_files.to_list(),
        arguments = [
            "-g",
            "-O",
            "binary",
            linking_outputs.executable.path,
            binary.path,
        ],
        executable = cc_toolchain.objcopy_executable,
    )

    return [
        DefaultInfo(
            files = depset([linking_outputs.executable, binary]),
        ),
        OutputGroupInfo(
            all_files = depset([linking_outputs.executable, binary]),
            elf_file = depset([linking_outputs.executable]),
            bin_file = depset([binary]),
        ),
    ]

kelvin_binary_impl = kelvin_rule(
    implementation = _kelvin_binary_impl,
    attrs = {
        "srcs": attr.label_list(allow_files = True),
        "deps": attr.label_list(allow_empty = True, providers = [CcInfo]),
        "hdrs": attr.label_list(allow_files = [".h"], allow_empty = True),
        "copts": attr.string_list(),
        "defines": attr.string_list(),
        "linkopts": attr.string_list(),
        "linker_script": attr.label(allow_single_file = True),
        "linker_script_includes": attr.label_list(default = [], allow_files = True),
        "_cc_toolchain": attr.label(default = Label("@bazel_tools//tools/cpp:current_cc_toolchain")),
    },
    fragments = ["cpp"],
    toolchains = ["@rules_cc//cc:toolchain_type"],
)

def kelvin_binary(
        name,
        srcs,
        tags = [],
        **kwargs):
    """A helper macro for generating binary artifacts for the kelvin core.

    This macro uses the kelvin toolchain, kelvin-specific starting asm,
    and kelvin linker script to build kelvin binaries.

    Args:
      name: The name of this rule.
      srcs: The c source files.
      tags: build tags.
      **kwargs: Additional arguments forward to cc_binary.
    Emits rules:
      filegroup              named: <name>.bin
        Containing the binary output for the target.
      filegroup              named: <name>.elf
        Containing all elf output for the target.
    """

    kelvin_binary_impl(
        name = name,
        srcs = srcs,
        linker_script = "@kelvin_sw//crt:kelvin_linker",
        tags = tags,
        **kwargs
    )

    # Need to create the following filegroups to make the output discoverable.
    native.filegroup(
        name = "{}.bin".format(name),
        srcs = [name],
        output_group = "bin_file",
        tags = tags,
    )
    native.filegroup(
        name = "{}.elf".format(name),
        srcs = [name],
        output_group = "elf_file",
        tags = tags,
    )

def kelvin_test(
        name,
        hw_test_size = "medium",
        hw_test_tags = [],
        iss_test_size = "small",
        iss_test_tags = [],
        **kwargs):
    """A sh_test wrapper for kelvin binaries

    A wrapper to build kelvin_binary and test it against build_tools/*test_runner.sh
    on both ISS and HW SystemC simulations.

    Args:
      name: The name of this rule.
      hw_test_size: Tests size for SystemC test, default to medium.
      hw_test_tags: Test tags passed to System test.
      iss_test_size: ISS test size. Default to small.
      iss_test_tags: Test tags passed to ISS test.
      **kwargs: Agruments that will be forwarded to kelvin_binary
    """

    kelvin_elf = "{}_elf".format(name)
    kelvin_binary(
        name = kelvin_elf,
        **kwargs
    )

    iss_test = "{}_iss".format(name)
    native.sh_test(
        name = iss_test,
        size = iss_test_size,
        srcs = [
            "//build_tools:test_runner.sh",
        ],
        args = [
            "$(location %s.elf)" % kelvin_elf,
        ],
        data = [
            "{}.elf".format(kelvin_elf),
        ],
        tags = ["iss"] + iss_test_tags,
    )

    hw_test = "{}_hw".format(name)
    native.sh_test(
        name = hw_test,
        size = hw_test_size,
        srcs = ["//build_tools:core_sim_test_runner.sh"],
        args = [
            "$(location %s.bin)" % kelvin_elf,
        ],
        data = [
            "{}.bin".format(kelvin_elf),
        ],
        tags = ["systemc"] + hw_test_tags,
    )

    native.test_suite(
        name = name,
        tests = [
            iss_test,
            hw_test,
        ],
    )

# From @tflite-micro//tensorflow/lite/micro/build_def.bzl, and paths
# modified to point to the external repo.
def generate_cc_arrays(name, src, out, visibility = None, tags = []):
    native.genrule(
        name = name,
        srcs = [
            src,
        ],
        outs = [
            out,
        ],
        tags = tags,
        cmd = "$(location @tflite-micro//tensorflow/lite/micro/tools:generate_cc_arrays) $@ $<",
        tools = ["@tflite-micro//tensorflow/lite/micro/tools:generate_cc_arrays"],
        visibility = visibility,
    )